Pls help my friend she need advice po

Yung kaibigan ko Po late Ng ilang araw daw period pero nagkaroon sya one day Lang. Ngpunta sya ob normal lng daw, nagaalala Kasi sya normal period nya never nadelay minsan daw advance. Saka 3 to 4. Days daw period nya may apps daw sya pangguide every period nya.... Nakailan pt daw sya negative nung 3 days delayed sya.